The Sea Shepherd anti-whaling group says banning activist Pete Bethune from the group was a legal strategy during his trial, and he is welcome to join its missions to Antarctica.
A Tokyo court gave Bethune a suspended two-year jail sentence on Wednesday after found him guilty of five charges related to boarding a Japanese whaling vessel in Antarctica in February, when he was part of a Sea Shepherd mission.
During his trial, the Sea Shepherd group said it was banning the activist from future trips, but leader Paul Watson says that was just a legal strategy. "I don't think he'll be going back this season, because I think he's going to be writing a book, which is good, but he's certainly welcome back in the future."
Mr Watson told Morning Report Japanese judges would have been hesitant to release Bethune if he was to return to the Southern Ocean. However, he said he was not aware of any deal on the matter being made with Japanese authorities.
New Zealand's Ministry of Foreign Affairs and Trade says it has no knowledge of a deal, and the Government's only involvement with Bethune has been to make sure he was treated as a Japanese person would be.
Sea Shepherd a 'criminal organisation'
A spokesperson for Japan's whaling programme says he does not believe the court decided to suspend the sentence because of Sea Shepherd's intervention.
Glenn Inwood, of the Institute for Cetacean Research, also says the suspended sentence should not be seen as a win for Sea Shepherd.
He says Bethune has been convicted on five charges, including a serious charge of assault, and the verdict demonstrates the protest group is a criminal organisation.
Ady Gil owner stands by Bethune
The American philanthropist who bought Pete Bethune's boat for its ill-fated Sea Shepherd expedition to the Southern Ocean says Japan must be held to account for the boat's loss.
Bethune said he boarded the Japanese whaling vessel to protest against what he says was the deliberate ramming of the Ady Gil, named after its purchaser, a Californian businessman.
Mr Gil says he doesn't blame Bethune for the $1.5 million vessel in Antarctic waters eventually sinking while being towed, and he also believes the Japanese whaling boat deliberately rammed it.
Labour's conservation spokesperson, Chris Carter, says the Government has a responsibility to investigate the collision.